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yasuhirokimura-db18/docs/api_reference/CXX/dbstream_write.html
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Yasuhiro KIMURA 9678929700 Update to 18.1.40
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<title>DbStream::write()</title>
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<p>Library Version 18.1.40</p>
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<th colspan="3" align="center">
<span xmlns="http://www.w3.org/1999/xhtml">DbStream::write()</span>
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<td width="20%" align="left"><a accesskey="p" href="dbstream_size.html">Prev</a> </td>
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External Files
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<hr />
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<div class="sect1" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="dbstream_write"></a>
<span>DbStream::write()</span>
</h2>
</div>
</div>
</div>
<pre class="programlisting">#include &lt;db_cxx.h&gt;
int
DbStream::write(Dbt *data, db_off_t offset, u_int32_t flags); </pre>
<p>
The <code class="methodname">DbStream::write()</code> method writes data
to an existing external file object in the database. This method
writes data contained in the <a class="link" href="dbt.html" title="Chapter 4.  The Dbt Handle">Dbt</a>
<span class="bold"><strong>data</strong></span> to the external file stream.
Data is written into the stream starting at the position indicated by
<span class="bold"><strong>offset</strong></span>. The amount of data
written is determined by the <code class="literal">size</code> field in the
Dbt.
</p>
<p>
If this method writes data in the middle of the external file, it will
overwrite existing data, instead of shifting it. If this method
writes data to the end of the external file, the data is appended to
the existing external file. You can determine how large an external
file is using <a class="xref" href="dbstream_size.html" title="DbStream::size()">
<span>DbStream::size()</span>
</a>.
</p>
<p>
To open a stream, use <a class="xref" href="dbstream.html" title="Dbc::db_stream()">
<span>Dbc::db_stream()</span>
</a>.
</p>
<p>
Unless otherwise specified, the
<code class="methodname">DbStream::write()</code> <span>
<span>
method either returns a non-zero error value or throws an
exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
</span>
</span>
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755608640464"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755608641712"></a>data</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>data</strong></span> parameter is
the <a class="link" href="dbt.html" title="Chapter 4.  The Dbt Handle">Dbt</a> containing the
data to be written to the external file. The amount of data
to be written is determined by the Dbt's
<code class="literal">size</code> field.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755608706000"></a>offset</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>offset</strong></span> parameter
identifies the position in the external file where the write
operation will begin.
</p>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755608685968"></a>flags</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>flags</strong></span> parameter must be
set to 0 or the following value:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p><a id="blobstream_DB_STREAM_SYNC_WRITE"></a>
<code class="literal">DB_STREAM_SYNC_WRITE</code>
</p>
<p>
A sync to disk operation is performed on the
stream at the end of the write operation. By
default, the sync is performed only when the
stream is closed using <a class="xref" href="dbstream_close.html" title="DbStream::close()">
<span>DbStream::close()</span>
</a>. Note that
this flag can also be specified when the stream is
created using <a class="xref" href="dbstream.html" title="Dbc::db_stream()">
<span>Dbc::db_stream()</span>
</a>, in which case the sync
behavior becomes the default behavior for this
stream instance.
</p>
</li>
</ul>
</div>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755608624128"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DbStream::write()</code> <span>
<span>
method may fail and throw a <a class="link" href="dbexception.html" title="Chapter 6. The DbException Class">DbException</a>
exception, encapsulating one of the following non-zero errors, or return one
of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idm139755608608352"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
An invalid flag value or parameter was specified; or if the
stream is read-only; or if the input Dbt was
configured with
<a class="link" href="dbt.html#dbt_DB_DBT_PARTIAL">DB_DBT_PARTIAL</a>.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755608615088"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="blob.html" title="Chapter 14.  External Files">DbStream</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idm139755608627520"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="blob.html#bloblist" title="External Files and Related Methods">External Files and Related Methods</a>
</p>
</div>
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